static void fe_to_4x(gfe4x* a, fe25519* b) {
  int i;
  unsigned char buf[32];

  fe25519_pack(buf, b);

  gfe4x_unpack_single(a, buf, 0);

  for (i = 0; i < 12; i++) {
    a->v[i].v[1] = a->v[i].v[0];
    a->v[i].v[2] = a->v[i].v[0];
    a->v[i].v[3] = a->v[i].v[0];
  }
}

static void ge_to_4x(ge4x* a, ge25519* b) {
  fe_to_4x(&a->x, &b->x);
  fe_to_4x(&a->y, &b->y);
  fe_to_4x(&a->z, &b->z);
  fe_to_4x(&a->t, &b->t);
}
